While flexible magnetic blend compositions have been known for some time, a high temperature oil resistant flexible rare earth magnetic material in strip form has continued to be a target for research and development. In particular, there has been interest in finding such a material for permanent magnet motors where the vastly increased performance of rare earth allows for lighter more powerful motor designs than those feasible with conventional bonded or sintered ferrite magnets. In addition, acoustical devices, copier rolls and instrumentation devices offer additional market possibilities for this material.
In particular, it has been known to use a conventional nitrile rubber system containing chemical curing agents, such as sulfur, for binders for use with rare earth particles. An example of such a product is sold by Polymag Incorporated, Belmont, N.Y., under the designation NEOMAG "70F" which uses "Magnequench", a Fe.sub.14 Nd.sub.2 B powder, made by Delco Remy, a division of General Motors, Anderson, Ind. It is believed that this product is made by an extrusion/rolling process to reach the final thickness and heat cured under pressure to crosslink the binder system. The final cured strip cannot be recycled or reprocessed. Aging of the sheet at temperatures above 100.degree. C. is rapid and causes embrittlement. In addition, the conventional nitrile binder in the magnet does a poor job in protecting the neodymium iron-boron powder from oxidation and the resultant rapid loss of magnetic properties.